Hex to Decimal - Swift

Question

Sorry if this seems really simple, I just can't find it anywhere online.

I have a UInt8 in hex, I need to get it to a decimal. How do I achieve this in swift?

For example:

"ff"

Thanks

possible duplicate of [How to convert hex number to bin in Swift?](http://stackoverflow.com/questions/26284223/how-to-convert-hex-number-to-bin-in-swift) — Amadan, Feb 20 '15 at 03:41
(if by "decimal" you mean a true `UInt8` like `255`, and not another string with decimal representation, `"255"`). — Amadan, Feb 20 '15 at 03:42

Rob · Accepted Answer · 2018-12-04T21:40:03.620

53

If you have a string representation, "ff", you can use UInt8(_:radix:):

let string = "ff"
if let value = UInt8(string, radix: 16) {
    print(value)
}

edited Dec 04 '18 at 21:40

answered Feb 20 '15 at 15:49

Rob

That last one works, except for one thing. All Ints are correct except 0. It returns nil instead of 0 and thne jumps to 1. Ideas? – JoeBayLD Feb 20 '15 at 23:12
I fixed it. Issue was var value: UInt8!. I made it var value: UInt8 = 0. Now it works. – JoeBayLD Feb 21 '15 at 18:15
Good catch. I've updated my answer accordingly. Thanks! – Rob Feb 21 '15 at 18:29
I've simplified my answer, excising `strtoul` from the answer. – Rob Oct 26 '16 at 22:17
I have FFFF hex string , total 16 bits so I used UInt16, thanks for the quick answer – Arpit B Parekh Jun 28 '22 at 10:53

score 5 · Answer 2 · answered Feb 20 '15 at 03:45

5

you can use the function strtoul to convert your hex to decimal:

let result = UInt8(strtoul("ff", nil, 16))  // 255

answered Feb 20 '15 at 03:45

Leo Dabus

That works. One more thing. If I print my NSData it's . I can convert to string and remove the first and last character. But is that the best way to do it? – JoeBayLD Feb 20 '15 at 03:49
2

@JoeBayLD You do _not_ to get the string representation and then convert that to binary. Use `getBytes` to get the binary data directly. – Rob Feb 20 '15 at 03:55
Thanks @Rob I just found this and appears to be working. I'll post a new question of the final product to make sure it's most efficient. http://stackoverflow.com/questions/25424831/cant-covert-nsdata-to-nsstring-swift – JoeBayLD Feb 20 '15 at 04:00

Jaywant Khedkar · Answer 3 · 2017-10-03T13:20:34.493

5

Try this code, It's work for me.

// Hex to decimal

let h2 = "ff"
let d4 = Int(h2, radix: 16)!
print(d4)

Hope this is help for some one

edited Oct 03 '17 at 13:20

answered Sep 20 '17 at 11:23

Jaywant Khedkar

score 4 · Answer 4 · answered Nov 22 '18 at 11:03

4

If your HEX value is not a String, but just something you want to convert compile-time, you can also use:

let integer : UInt8 = 0xff

So prefixing it with 0x will do the job.

answered Nov 22 '18 at 11:03

Aron K.

4 Answers4